magistrsko delo
Barbara Fojkar (Author), Domen Leštan (Mentor), Zalika Črepinšek (Thesis defence commission member), Helena Grčman (Thesis defence commission member)

Abstract

Blato je stranski produkt komunalnih čistilnih naprav, ki poleg drugih onesnaževal vsebuje potencialno strupene kovine (PSK). Ravno te omejujejo njegovo uporabo v kmetijstvu, saj presegajo mejne vrednosti, ki so zakonsko določene. Uporaba remediiranega blata v kmetijstvu vodi v trajnosten način upravljanja z blatom zaradi vrnitve organske snovi in hranil, še posebej fosforja, v tla. V magistrski nalogi smo uporabili že obstoječo tehnologijo odstranjevanja PSK iz blata čistilnih naprav in jo prilagoditi za potencialno uporabo kot del postopka na čistilnih napravah. Kot kelatno sredstvo za vezavo in odstranjevanje PSK smo uporabili EDTA. V prvem delu poskusa smo primerjali različne koncentracije EDTA in ugotovili, da ima 35 mM EDTA najboljše razmerje med odstranitvijo PSK in cenovno dostopnostjo. Z izbrano koncentracijo EDTA smo nato izpirali blato, sestavljeno iz anaerobnega in aerobnega blata v razmerju 1:8. V anaerobnem delu poskusa smo med inkubacijo vzorcev opazovali vpliv EDTA na produkcijo metana, kasneje pa smo iz blata odstranili železo, saj njegova prisotnost v blatu kasneje ovira odstranitev ostalih kovin. Ugotovljeno je bilo, da EDTA nima vpliva na metanogenezo, dodatek citronske kisline pa ta proces pospeši. V aerobnem delu poskusa smo iz blata odstranili preostale PSK s trikratnim spiranjem. Na podlagi meritev blata, procesnih raztopin in trdnega odpada smo določili učinkovitost odstranitve PSK iz blata. Ugotovili smo, da je odstranitev PSK iz blata zadostna, da koncentracije v njem upadejo pod zakonsko določene mejne vrednosti za uporabo v kmetijstvu. Vsebnost fosforja se v blatu pred in po remediiaciji bistveno ne razlikuje. Prav tako smo v poskusu uspešno reciklirali EDTA in procesne raztopine, ki prispevajo k trajnosti postopka, saj ne proizvaja odpadne vode.

Keywords

EDTA;blato komunalnih čistilnih naprav;potencialno strupene kovine;oprano blato;trajnost;anaerobna razgradnja;aerobna obdelava;proizvodnja metana;fosfor;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [B. Fojkar]
UDC: 628.3:502.175(043.2)
COBISS: 164902403 Link will open in a new window
Views: 13
Downloads: 2
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Other data

Secondary language: English
Secondary title: Use of EDTA to treat sewage sludge contaminated with toxic metals
Secondary abstract: Sludge is a by-product of municipal sewage treatment plants, which, in addition to other pollutants, contains potentially toxic metals (PTM). It is precisely these that limit its use in agriculture, as they exceed the limit values set by law. The use of remedied sludge in agriculture leads to a sustainable method of sludge management due to the return of organic matter and nutrients, especially phosphorus, to the soil. In the master's thesis, we used an already existing technology of PTM removal from sewage sludge and adapted it for potential use as part of the process at sewage treatment plants. EDTA was used as a chelating agent for PTM binding and removal. In the first part of the experiment, we compared different concentrations of EDTA and found that 35 mM EDTA has the best ratio between PTM removal and affordability. The selected concentration of EDTA was then used to wash the sludge, consisting of anaerobic and aerobic sludge in a ratio of 1:8. In the anaerobic part of the experiment, we observed the effect of EDTA on methane production during the incubation of the samples, and later iron was removed from the sewage sludge, as its presence later hinders the removal of other metals. It was found that EDTA has no effect on methanogenesis, and the addition of citric acid accelerates this process. In the aerobic part of the experiment, the remaining PTM were removed from the mud by washing it three times. Based on measurements of sludge, process solutions and waste, we determined the efficiency of PTM removal from sludge. We found that the removal of metals from the sludge is sufficient for the concentrations to fall below the legal limit values for use in agriculture. The phosphorus content in the sludge before and after remediation does not differ significantly. We also successfully recycled EDTA and process solutions in the experiment, which contributes to the sustainability of the process, as it does not produce waste water.
Secondary keywords: sewage sludge;potentially toxic metals;washed sludge;sustainability;anaerobic digestion;aerobic treatment;methane production;phosphorus;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za agronomijo
Pages: 1 spletni vir (1 datoteka PDF (X, 45 str., [6] str. pril.))
ID: 19945554